Implications of the Propagation Method for the Phytochemistry of Nepeta cataria L. throughout a Growing Season.

Catnip (Nepeta cataria L.) plants produce a wide array of specialized metabolites with multiple applications for human health. The productivity of such metabolites, including nepetalactones, and natural insect repellents is influenced by the conditions under which the plants are cultivated. In this study, we assessed how field-grown catnip plants, transplanted after being propagated via either single-node stem cuttings or seeds, varied regarding their phytochemical composition throughout a growing season in two distinct environmental conditions (Pittstown and Upper Deerfield) in the state of New Jersey, United States. Iridoid terpenes were quantified in plant tissues via ultra-high-performance liquid chromatography with triple quadrupole mass spectrometry (UHPLC-QqQ-MS), and phenolic compounds (phenolic acids and flavonoids) were analyzed via UHPLC with diode-array detection (UHPLC-DAD). The highest contents of total nepetalactones in Pittstown were found at 6 weeks after transplanting (WAT) for both seedlings and cuttings (1305.4 and 1223.3 mg/100 g, respectively), while in Upper Deerfield, the highest contents for both propagules were at 11 WAT (1247.7 and 997.1 mg/100 g, respectively) for seed-propagated and stem cuttings). The highest concentration of nepetalactones was associated with floral-bud to partial-flowering stages. Because plants in Pittstown accumulated considerably more biomass than plants grown in Upper Deerfield, the difference in nepetalactone production per plant was striking, with peak productivity reaching only 598.9 mg per plant in Upper Deerfield and 1833.1 mg per plant in Pittstown. Phenolic acids accumulated in higher contents towards the end of the season in both locations, after a period of low precipitation, and flavone glycosides had similar accumulation patterns to nepetalactones. In both locations, rooted stem cuttings reached their maximum nepetalactone productivity, on average, four weeks later than seed-propagated plants, suggesting that seedlings have, overall, better agronomic performance.

Phytophthora capsici, 100 Years Later: Research Mile Markers from 1922 to 2022.

In 1922, Phytophthora capsici was described by Leon Hatching Leonian as a new pathogen infecting pepper (Capsicum annuum), with disease symptoms of root rot, stem and fruit blight, seed rot, and plant wilting and death. Extensive research has been conducted on P. capsici over the last 100 years. This review succinctly describes the salient mile markers of research on P. capsici with current perspectives on the pathogen's distribution, economic importance, epidemiology, genetics and genomics, fungicide resistance, host susceptibility, pathogenicity mechanisms, and management.

First report of Powdery Mildew Caused by Golovinomyces ambrosiae on Industrial Hemp in New Jersey.

In December 2019, New Jersey became one of the first states to have its industrial hemp (Cannabis sativa L.) plan approved by the U.S. Department of Agriculture (USDA) following enactment of the 2018 Farm Bill that authorized the production of hemp. Following this approval, hemp was legally grown for the first time in 2020. During the growing seasons of 2020 and 2021, powdery mildew-like symptoms were observed during the summer months (Jun to Aug) in greenhouse hemp research and fall months (Aug to Oct) in field production plots on Rutgers Agricultural Experiment Station farms in southern and northern New Jersey. Symptoms were observed on leaves and stems of hemp cultivars 'CB Genius', 'Cherry Wine' and 'Bay Mist'. Symptoms initially appeared as small white patches of mycelia and conidia on the adaxial surface of leaves that gradually spread to entire leaves and stems. Leaf discoloration (e.g., chlorosis) and premature leaf drop were observed. More severe symptoms and damage were observed in the greenhouse than outdoor cultivation. A voucher specimen was deposited in the U.S National Fungus Collections, USDA-ARS, Beltsville, MD (accession number 929187). Morphological examination of the white colonies from the cultivar 'Baymist' was carried out using light microscopy and further characterized by sequencing. This isolate was labelled PMH2. Hyphae were septate, conidiophores were hyaline, unbranched, measuring 130 to 240 µm in length and produced 1 to 4 conidia in chains. Conidia were hyaline, ellipsoid to ovoid in shape and measured 20 to 36 ×10 to 18 µm (n=30). Oil-like drops were present within conidia, although no distinct fibrosin bodies were observed. Chasmothecia were not observed. Morphological observations were consistent with those of Golovinomyces spp. as described by Braun and Cook (2012). Morphological observations (conidiophore and conidial measurements) were also similar to the description of G. ambrosiae on Hemp, as described in Wiseman et al, 2021. Sequencing of internal transcribed spacer (ITS), large ribosomal subunit (28S), intergenic spacer (IGS), beta- tubulin (TUB2) and chitin synthase 1(CHS1) region, were carried out with the primer sets ITS5/ITS4, LSU1/LSU2, IGS-12a/NS1R, TubF1/TubR1 and gCS1a1/gCS1b respectively, as shown by Qiu et al. (2020). Maximum-likelihood phylogenetic analysis confirmed the grouping of the PMH2 isolate within the G. ambrosiae accessions. Each individual gene alignment was treated as a separate partition. Sequences were not concatenated for maximum -likelihood phylogenetic analysis. Sequence data were deposited in GenBank under the accessions OK626453 (ITS), OK626454 (28S), OL456201 (IGS), OL415512 (TUB2) and OL415513(CHS1). To fulfill Koch's postulates, two mature, potted plants of C. sativa cv. 'Alpha Explorer' were inoculated by gently pressing symptomatic hemp leaves onto their leaf surface. They were incubated in an indoor grow room at 23°C and relative humidity of 50%. Non-inoculated healthy plants of C. sativa cv. 'Alpha Explorer' served as control. Inoculated plants developed powdery mildew symptoms within 10 to 12 days, while all control plants were asymptomatic. The powdery mildew on inoculated plants was found to be morphologically similar to the original. G. ambrosiae has been reported on C.sativa in Oregon (Wiseman et al. 2021) and G. ambrosiae (as G. spadiceus) has been reported on Cannabis in Kentucky (Szarka et al. 2019), Ohio (Farinas and Hand 2020) and New York (Weldon et al. 2020). This is the first known report of Golovinomyces ambrosiae causing powdery mildew on hemp in New Jersey. With the recent opening ( Dec15, 2021) of cultivation licensing and retailing of recreational marijuana, the acreage of Hemp production in New Jersey is expected to significantly increase, particularly for greenhouse production. It is important to document the species to develop management strategies to control this disease.

Population structure, genetic diversity and downy mildew resistance among Ocimum species germplasm.

BACKGROUND: The basil (Ocimum spp.) genus maintains a rich diversity of phenotypes and aromatic volatiles through natural and artificial outcrossing. Characterization of population structure and genetic diversity among a representative sample of this genus is severely lacking. Absence of such information has slowed breeding efforts and the development of sweet basil (Ocimum basilicum L.) with resistance to the worldwide downy mildew epidemic, caused by the obligate oomycete Peronospora belbahrii. In an effort to improve classification of relationships 20 EST-SSR markers with species-level transferability were developed and used to resolve relationships among a diverse panel of 180 Ocimum spp. accessions with varying response to downy mildew. RESULTS: Results obtained from nested Bayesian model-based clustering, analysis of molecular variance and unweighted pair group method using arithmetic average (UPGMA) analyses were synergized to provide an updated phylogeny of the Ocimum genus. Three (major) and seven (sub) population (cluster) models were identified and well-supported (P < 0.001) by PhiPT (ΦPT) values of 0.433 and 0.344, respectively. Allelic frequency among clusters supported previously developed hypotheses of allopolyploid genome structure. Evidence of cryptic population structure was demonstrated for the k1 O. basilicum cluster suggesting prevalence of gene flow. UPGMA analysis provided best resolution for the 36-accession, DM resistant k3 cluster with consistently strong bootstrap support. Although the k3 cluster is a rich source of DM resistance introgression of resistance into the commercially important k1 accessions is impeded by reproductive barriers as demonstrated by multiple sterile F1 hybrids. The k2 cluster located between k1 and k3, represents a source of transferrable tolerance evidenced by fertile backcross progeny. The 90-accession k1 cluster was largely susceptible to downy mildew with accession 'MRI' representing the only source of DM resistance. CONCLUSIONS: High levels of genetic diversity support the observed phenotypic diversity among Ocimum spp. accessions. EST-SSRs provided a robust evaluation of molecular diversity and can be used for additional studies to increase resolution of genetic relationships in the Ocimum genus. Elucidation of population structure and genetic relationships among Ocimum spp. germplasm provide the foundation for improved DM resistance breeding strategies and more rapid response to future disease outbreaks.

Basil Downy Mildew (Peronospora belbahrii): Discoveries and Challenges Relative to Its Control.

Basil (Ocimum spp.) is one of the most economically important and widely grown herbs in the world. Basil downy mildew, caused by Peronospora belbahrii, has become an important disease in sweet basil (O. basilicum) production worldwide in the past decade. Global sweet basil production is at significant risk to basil downy mildew because of the lack of genetic resistance and the ability of the pathogen to be distributed on infested seed. Controlling the disease is challenging and consequently many crops have been lost. In the past few years, plant breeding efforts have been made to identify germplasm that can be used to introduce downy mildew resistance genes into commercial sweet basils while ensuring that resistant plants have the correct phenotype, aroma, and tastes needed for market acceptability. Fungicide efficacy studies have been conducted to evaluate current and newly developed conventional and organic fungicides for its management with limited success. This review explores the current efforts and progress being made in understanding basil downy mildew and its control.

Evaluation of Fungicides for the Control of Peronospora belbahrii on Sweet Basil in New Jersey.

Basil downy mildew (BDM), caused by the fungus-like oomycete pathogen Peronospora belbahrii, has become a destructive disease of sweet basil (Ocimum basilicum). Without proper management, BDM can cause complete crop loss. Currently, there are no commercially available sweet basil cultivars with genetic resistance to BDM. Because BDM is a relatively new disease of basil in the United States, there are few currently registered conventional or organic fungicides labeled for its control. Fungicide efficacy trials were conducted in 2010 and 2011 at Rutgers Agricultural Research and Extension Center in Bridgeton, NJ. During both years, seven biological fungicide treatments were field evaluated, including hydrogen dioxide; extract of Reynoutria sachalinensis; Bacillus pumilus strain QST 2808; a mixture of rosemary oil, clove oil, and thyme oil; mono- and dipotassium salts of phosphorous acid; sesame oil; copper hydroxide; and a combination of sesame oil + cupric hydroxide. Six conventional fungicides evaluated included mandipropamid, fluopicolide, propamocarb hydrochloride, cyazofamid, azoxystrobin, and fenamidone. In both years, mono- and dipotassium salts of phosphorous acid provided the best control. Moderate disease suppression was provided by mandipropamid, cyazofamid, and fluopicolide compared with the control in 2010 and mandipropamid, cyazofamid, and copper hydroxide compared with the control in 2011.